1. Field of the Invention
The present invention is generally related to a marine vessel having two marine propulsion devices and, more particularly, to a method for slowing the forward movement of the marine vessel by appropriately changing the physical positions of the marine propulsion devices relative to the hull of the marine vessel.
2. Description of the Related Art
Many different types of marine propulsion systems are known to those skilled in the art. These include outboard motors, sterndrive devices, and systems in which one or more marine drives extend downwardly through the hull of the marine vessel.
U.S. Pat. No. 5,735,718, which issued to Ekwall on Apr. 7, 1998, describes a drive unit for a boat having an engine with a flywheel surrounded by a flywheel casing, a propeller drive housing connected to, but electrically insulated from, the flywheel casing, and an input shaft for the propeller drive housing which is driven and electrically insulated from the flywheel.
U.S. Pat. No. 5,755,605, which issued to Äsberg on May 26, 1998, describes a propeller drive unit. The drive installation in a boat has two propeller drive units which extend out through individual openings in the bottom of a V-bottomed boat, so that the legs are inclined relative to each other. The leg of one drive unit can be set to turn the boat in one direction at the same time as the leg of the other drive unit can be set to turn the boat in the opposite direction, so that the horizontal counteracting forces acting on the legs cancel each other, while the vertical forces are added to each other to trim the running position of the boat in the water.
U.S. Pat. No. 6,234,853, which issued to Lanyi et al. on May 22, 2001, discloses a simplified docking method and apparatus for a multiple engine marine vessel. A docking system is provided which utilizes the marine propulsion unit of a marine vessel, under the control of an engine control unit that receives command signals from a joystick or push button device, to respond to a maneuver command from the marine operator. The docking system does not require additional propulsion devices other than those normally used to operate the marine vessel under normal conditions. The docking or maneuvering system uses two marine propulsion units to respond to an operator's command signal and allows the operator to select forward or reverse commands in combination with clockwise or counterclockwise rotational commands either in combination with each other or alone.
U.S. Pat. No. 6,431,928, which issued to Aarnivuo on Aug. 13, 2002, describes an arrangement and method for turning a propulsion unit. A propeller drive arrangement for moving and steering a vessel traveling in the water is described. The propeller drive arrangement includes an azimuthing propulsion unit, a power supply, a control unit, and a sensor means. An operating means is provided for turning the azimuthing propulsion unit in relation to the hull of the vessel for steering the vessel in accordance with a steering command controlled by the vessel's steering control device. The operating means also includes a second electric motor for turning the azimuthing propulsion unit via a mechanical power transmission that is connected to the second electric motor.
U.S. Pat. No. 6,623,320, which issued to Hedlund on Sep. 23, 2003, describes a drive means in a boat. A boat propeller drive with an underwater housing which is connected in a fixed manner to a boat hull and has tractor propellers arranged on that side of the housing facing ahead is described. Arranged in that end portion of the underwater housing facing a stern is an exhaust discharge outlet for discharging exhaust gases from an internal combustion engine connected to the propeller drive.
U.S. Pat. No. 6,688,927, which issued to Aarnivuo on Feb. 10, 2004, describes an arrangement and method for turning a propulsion unit. The arrangement comprises an azimuthing propulsion unit and operating equipment for turning the azimuthing propulsion unit to steer the vessel. The operating equipment comprises an electric motor for rotating the propulsion unit by means of a mechanical power transmission machinery connected to the electric motor. A power unit supplies electric power to the electric motor. A control unit controls the operation of the electric motor by controlling the power unit.
U.S. Pat. No. 6,712,654, which issued to Putaansuu on Mar. 30, 2004, describes the turning of a propulsion unit. It is a method and apparatus for moving and steering a vessel traveling in water. The arrangement for moving and steering a vessel includes a propulsion unit having a chamber positioned outside the vessel equipment for rotating a propeller arranged in connection with the chamber, and a shaft means connected to the chamber for supporting the chamber in a rotatable manner at the hull of the vessel. At least one hydraulic motor is used for turning the shaft means in relation to the hull of the vessel for steering the vessel. The arrangement also includes a means for altering the rotational displacement of the hydraulic engine.
U.S. Pat. No. 6,705,907, which issued to Hedlund on Mar. 16, 2004, describes a drive means in a boat. A boat propeller drive with an underwater housing which is connected in a fixed manner to a boat hull and has tractor propellers arranged on that side of the housing facing ahead is described. In the rear edge of the underwater housing, a rudder blade is mounted for pivoting about a vertical rudder axis.
U.S. Pat. No. 6,783,410, which issued to Florander et al. on Aug. 31, 2004, describes a drive means in a boat. A boat propeller drive unit with an underwater housing is described. The housing is solidly joined to a boat hull and has pulling propellers on the forward facing side of the housing. At the aft edge of the underwater housing, a rudder is mounted, comprising a first rudder blade mounted in the underwater housing and a second rudder blade mounted on the aft edge of the first rudder blade.
International Patent Application WO 03/042036, which was filed by Arvidsson, describes a remote control system for a vehicle. The system comprises a primary heading sensor fixedly attached to the vehicle which is adapted to detect a reference heading. It also comprises a remote control unit which comprises a steering input manipulator. The remote control unit is either portable by a user or rotationally attached to the vehicle relative to a main axis of the vehicle. It is adapted to communicate steering input data to a steering computer which is programmed to process the steering input data into steering commands and to communicate the steering commands to a steering mechanism of the vehicle.
International Patent Application WO 03/093105, which was filed by Mansson, describes a boat hull with an outboard drive and outboard drive for boats. The boat hull has an outboard drive unit which comprises an underwater housing mounted on the outside of the hull bottom and a gear housing mounted on the inside of the hull bottom and joined to the underwater housing. Between the underwater housing and the gear housing there is fixed a mounting plate, which, together with a screw down plate, with elastic ring inserts, fixes the drive unit to a flange, which is made on the inside of a well surrounding an opening in the hull bottom.
International Patent Application WO 03/093106, which was filed by Arvidsson et al., describes an outboard drive for boats. It comprises an underwater housing, in which two propeller shafts are mounted and are driven via a first bevel gearing enclosed in the underwater housing, and a second bevel gearing enclosed in a gear housing. With the aid of a mounting element joined to the underwater housing and the gear housing, the drive unit can be mounted in an opening in the bottom of a boat hull, with the underwater housing on the outside and the gear housing on the inside of the hull. The mounting element forms a housing which defines, firstly, an oil reservoir for the oil of the drive unit and, secondly, a surrounding chamber through which engine cooling water flows and which is used for cooling the oil in the reservoir.
International Patent Application WO 02/093102, which was filed by Arvidsson et al., describes a method of steering a boat with double outboard drives and a boat having double outboard drives. A method of steering a planing V-bottomed boat with double individual steerable outboard drive units with underwater housings is described. The underwater housings extend down from the bottom of the boat. When running at planing speed straight ahead, the underwater housings are set with “toe-in”. In other words, the underwater housings are inclined towards each other with opposite angles of equal magnitude relative to the boat centerline. When turning, the inner drive unit is set with a greater steering angle than the outer drive unit.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
When a marine vessel is operating at planing speeds and the operator of the vessel wishes to cause the vessel to stop, the operator typically moves a throttle handle from a forward velocity position to either neutral or reverse. In certain circumstances, where the operator of the marine vessel determines that a sudden stop is required, the manually controlled throttle handle can be moved rapidly from a forward velocity position to a reverse velocity position. This causes the propellers of the marine propulsion units to rapidly stop their rotation and then reverse their rotation to more rapidly slow the marine vessel and bring it to a stop. This circumstance would typically be employed in an emergency situation where the marine vessel operator determines that an immediate stop is necessary. When propellers are suddenly reversed, significant cavitation often occurs and the efficiency of the braking force caused by the reverse propellers is adversely affected. It would therefore be beneficial if a more effective braking technique could be provided to rapidly slow the forward advance of a marine vessel.